When they dock with the ISS on Friday, the trio will join the current three person crew who will remain on the station for several more months rather than heading back home as has been the case previously.

This will raise the station's permanent crew to six for the first time, allowing the astronauts to make full use of the capacities of the ISS, which orbits 350 kilometres (220 miles) above Earth.

"It's a very good example that shows the whole world that when countries want to work together for the good of their children we can do incredible things," said De Winne at a news conference in Baikonur ahead of his departure.

"It would be impossible for one country to maintain six people aboard the space station. But thanks to the international cooperation, not just aboard the ISS but between all the space organizations, it will be possible."

The three will be joining Russian Gennady Padalka, US astronaut Michael Barratt and Japan's Koichi Wakata aboard the station.

De Winne will take over from Padalka as commander of the ISS when the crew is rotated in October, the first time a West European has been given this responsibility. The Belgian will then return to earth in November.

In a mission marked by a sequence of firsts, Friday's docking will also mark the first time all the partners in the station -- the United States, Russia, Europe, Japan and Canada -- will be represented at the same time onboard.

De Winne is only the second European astronaut to undertake a full six month mission to space after the German Thomas Reiter in 2006. Italian Paolo Nespoli is due to carry out a similar mission from November 2010.

The European Space Agency (ESA) now receives 8.3 per cent of the experiment time aboard the ISS, meaning that it can send an astronaut to the station for a six month mission every two years.

The astronauts will hurtle into low Earth orbit on Wednesday and then make a gradual ascent to the station over two days.

The station has become a sophisticated platform for scientific experiments after the installation of a European laboratory last year and the arrival of a hi-tech Japanese lab, Kibo, which is currently being completed.

A huge new solar array was installed earlier this year to give more power.

Amid a dizzying array of new technology, one feature new arrivals will have to get used to is a recycling facility installed this month that enables astronauts to drink their recycled urine.

In one study to be carried out on the station, Thirsk, 55, will take medication usually prescribed to geriatric patients to counter the effects of bone loss in space.

The voyage also marks a rise in the frequency of manned flights aboard the Soyuz, a Soviet-designed rocket that originated in the late 1960s.

Russia is stepping up the number of Soyuz launches from two in previous years to four this year to meet the demands of the ISS.

The Soyuz is also set to become the sole means of reaching the ISS for a several years when the United States takes its space shuttles out of commission in 2010.